Google Earth (an application/program that you download) is a fairly powerful tool available for free.
It has different measuring tools that I use often - measure distances, perimeter measurements, area measurements. I import data from my GPS unit to the program - such as points of interest, or elevation data, trail routes etc.
Satellite images are very useful, being able to browse the history of the images can also be quite telling. Images from different times of year can be used to understand the composition of a forest, for example. I can easily map out deciduous vs. conifer stands this way. Depending on location you may could have 10+ images spanning 10+ years.
There are other programs that perform these functions as well.
Bernetta, you might try your county admin website. GIS (geographic information systems) plat maps are often available online and searchable by property address. These usually have beautiful satellite images and options for a lot of other things such as topo lines and flood areas.
The USDA has an online Web Soil Survey. It's also free and will map out your property in terms of soil types. I was surprised to learn that I have three different categories of soil on our property. That helped us better plan the garden and orchard.
I also use google earth, but key to my process is use of backcountry navigator on my phone to place named waypoints as I explore; then I load the gps coordinates into google earth to flesh out the map.
There are plenty of alternatives to backcountry navigator, but using something for this purpose is very useful.
'Theoretically this level of creeping Orwellian dynamics should ramp up our awareness, but what happens instead is that each alert becomes less and less effective because we're incredibly stupid.' - Jerry Holkins
Definitely check your county to see what GIS they provide. My county provides a wealth of map info - contours, historical aerial views, and LIDAR - which is perhaps the most interesting for viewing the terrain (it shows 70 year old tire tracks from logging).
the Soil Survey is the only one that shows you the different soil types.
On my phone I have "Topo Maps" that shows me satellite photos overlayed with contour lines. It allows me to mark points and track me if I want (sort of shows trails and proto-trails). That's helpful for looking at areas after the fact, perhaps on the big desktop instead.
Here's my planned app workflow, which is very heavy on Google products:
1) County GIS sites.
I adjust settings to ensure water features and contour lines are enabled -- both of course being crucial for permaculture design.
I do a "print screen" snapshot of the GIS.
I go to the parcel(s) in question, and transcribe GPS coordinates from the boundary corners of the area, putting them into...
2) Google Earth Pro.
I create a series of polygons on Google Earth Pro for the general area of interest.
I insert the snapshot from the GIS website as an image overlay into Google Earth Pro, and adjust the opacity to see contour lines and land character.
With the GIS image overlay plus Google Earth, I can better analyze the contours and features, and then I can add pins (potential Keypoint locations, springs, wells, access points, Zone 0 origin), paths (potential Keylines, rivers creeks and gullies, access paths), measure distances for reference, and draw polygons to measure acreages or areas for various zones and planting plans. The areas can also help analyze potential water capture volume for swales or ponds.
After I have a fair understanding of the land and points/lines/areas of interest, I save it to a KML file, and then import it into...
3) Google Maps.
Specifically, the "My Maps" feature.
I can import the KML from Google Earth, and place the key zones and areas and points onto a shareable My Map. Then any stakeholders (or clients) can have a reference on their smartphone or tablet when walking the property.
4) Google Photos and smartphone camera.
Now that I finally own a smartphone, I can take GPS tagged photos. "Oh there is a fruit tree here." "Ah, here's the precise location of the creek" etc. "The view-scape from this point is great. Maybe we'll add a structure here?"
Later I can add these reference points as "pins" to the Google Earth working map, or to My Maps for an outwardly sharable stakeholder map.
I may also use the GPS from my Fitbit to save a trail of where I walk on the property for later reference... but I am looking for something smartphone based for my breadcrumb trials now.
What is a good recommended smartphone app for mapping trails as breadcrumbs while walking, which saves to a KML file?
That would really help me with my planned workflow.
5) Drawing software: GIMP and Inkscape.
My next phase will be taking the zones, lines, and points of interest from the walkthrough and my basemaps, and doing more precise mapping of design concepts for planting and structure.
Both of the above drawing apps are open source, and support "layers". (So, for a food forest, I could have a layer for trees, a layer for herbs, a layer for ground covering.)
The layering feature also allows the concepts to be viewed on top of a birds eye view of the area of interest.
I've also used Google Slides for a simple plan-view mapping of where to plant trees.
6) Google Docs
In sequence with all the mapping and drawing and ideating taking place, I can use Google Docs, Sheets, and Slides for further stakeholder writeup, planting lists, cost estimates, SOPs, and presentations of concepts.
I can store all this in a shareable folder. All for free.